A variety of vending machines are known and intensively installed in different locations indoors as well as outdoors for selling different things. Conventional vending machines commonly accept coins only. There are also know certain vending machines which accept paper money. These vending machines which accept paper money simply comprises a paper money recognition mechanism and a paper money transmission mechanism. In order to prevent the inserted paper money from being obtained by stealing, hook means are commonly installed to prohibit the inserted paper money from being pulled out of the machine. However, this security installation may cause the received paper money to be damaged when thieves try to steal the money.
The paper money recognition and transmission system of the aforesaid co-pending parent application of the present invention was developed under the circumstances in view. This structure of paper money recognition and transmission system comprises a housing, an upper mainframe, a lower mainframe, a transmission unit, and a paper money recognition circuit. The transmission unit carries the inserted paper money forward when the inserted paper money is recognized. When a paper money is inserted into the vending machine, the front sensor of the paper money recognition circuit is triggered to send a signal to a step motor causing it to drive the transmission unit, and therefore the inserted paper money is carried through the upper mainframe and the lower mainframe into a money box. Before entering the money box, the rear sensor of the paper money recognition circuit-is turned on to recognize the inserted paper money. If the inserted paper money is a counterfeit paper money, the step motor will be turned in the reversed direction to send the counterfeit paper money back to the paper money slot. If the inserted paper money is recognized as true money, the paper money will be delivered to the money box.